The microwave oven was invented purely by accident. During WWII, an engineer named Percy Spencer was perfecting radars for the Army. He noticed that his dinner, which was on the table, got hot. He immediately made the connection with the device he was working on. Quickly, he experimented to see if his hypothesis was true, by using popcorn, eggs, etc. Unfortunately, the way the oven functions was not well known at the time and several engineers, over half in fact, who were working to develop the practical application of this discovery, died of cancer. It must be noted that a microwave oven does not heat up! It emits waves that excite the water molecules inside the food. To put it simply, the molecules vibrate faster and they accumulate energy. This energy is transformed into heat and… dinner is ready!